Ron \Pigpen\" McKernan" Grateful Dead What was special about the grateful dead? The Dead's early sets centered around blues and R&B covers chosen by McKernan. By the end of 1966, what happened in 1966? the end of 1966, Garcia had improved his musical skills and wanted to assert himself more as a leader and musical director, leader of what? and musical director, changing the band's direction and reducing McKernan's contributions.
how did he change the direction
how did Garcia change the direction?
Along with Garcia and second guitarist Bob Weir, McKernan was a participant in the predecessor groups leading to the formation of the Grateful Dead, beginning with the Zodiacs and Mother McCree's Uptown Jug Champions. Drummer Bill Kreutzmann was added and the band evolved into the Warlocks. Around 1965, McKernan urged the rest of the Warlocks to switch to electric instruments. Bassist Phil Lesh joined soon after, and they became the Grateful Dead. The group were keen to involve McKernan in the band, as he was the group's original leader and was considered the best singer and frontman.  The Dead's early sets centered around blues and R&B covers chosen by McKernan. By the end of 1966, Garcia had improved his musical skills and wanted to assert himself more as a leader and musical director, changing the band's direction and reducing McKernan's contributions. In 1967, drummer Mickey Hart joined the Grateful Dead, followed by classically trained keyboardist Tom Constanten in 1968, further changing the group's style. Constanten often replaced McKernan on keyboards in the studio, as McKernan found it difficult to adapt to the new material that Garcia and Lesh composed for the band.  In October 1968, McKernan and Weir were nearly fired from the band after Garcia and Lesh believed their playing was holding the band back from lengthy and experimental jamming. Garcia delegated the task of firing them to Rock Scully, who said that McKernan "took it hard." Weir promised to improve, but McKernan was more stubborn. According to Garcia biographer Blair Jackson, McKernan missed three Dead shows before vowing not to "be lazy" any more and rejoining, while Kreutzmann objected to replacing McKernan and said the event never happened. Following his discharge from the United States Air Force in November 1968, Constanten officially joined the band, having only worked in the studio while on leave up to that point. Road manager Jon McIntire commented that "Pigpen was relegated to the congas at that point and it was really humiliating and he was really hurt, but he couldn't show it, couldn't talk about it." He began to take Hammond organ lessons and learned how to use the various drawbars and controls.  After Constanten's departure in January 1970 over musical and lifestyle differences, McKernan nominally resumed keyboard duties. He contributed instrumentation to only two tracks (Hammond organ on "Black Peter" and harmonica on "Easy Wind", the latter as lead vocalist) on Workingman's Dead (1970), the band's breakthrough studio release. On the follow-up album American Beauty, keyboard parts were handled by Garcia and Lesh, along with session musicians Howard Wales and Ned Lagin. The 1971 live album Grateful Dead featured three overdubbed organ parts from Merl Saunders in addition to McKernan's contributions on "Big Railroad Blues", "The Other One", and "Me & Bobby McGee". While Garcia expressed frustration at McKernan's missed rehearsals and his inability to keep up with new material, Lesh was more forgiving, opining that "it was okay for Pigpen to lay out... we kept wanting Pigpen to be there because he was 'one of us.'" CANNOTANSWER
contributions. In 1967, drummer Mickey Hart joined the Grateful Dead, followed by classically trained keyboardist Tom Constanten in 1968,
An aerogravity assist, or AGA, is a theoretical spacecraft maneuver designed to change velocity when arriving at a body with an atmosphere.  A pure gravity assist uses only the gravity of a body to change the direction of the spacecraft trajectory.  The change in direction is limited by the mass of the body, and how closely it can be approached.  An aerogravity assist uses a closer approach to the planet, dipping into the atmosphere, so the spacecraft can also use aerodynamic lift with upside-down wings to augment gravity and further curve the trajectory.  This enables the spacecraft to deflect through a larger angle, resulting in a higher delta-v (change in velocity).  This in turn allows a shorter travel time, a larger payload fraction of the spacecraft, or a smaller spacecraft for a given payload.

The related techniques of  aerocapture, aerobraking, and atmospheric entry also attempt to use the body's atmosphere to help reduce propulsion requirements.  In an aerogravity assist, however, the goal is not to use the atmosphere to slow the spacecraft down, but instead use it to achieve a larger change in direction.

While the use of an aerogravity assist has been proposed for a variety of missions, including the capture of a spacecraft into orbit about Saturn, the technique has not yet been used in practice.

See also
Planetary flyby
Flyby (spaceflight)

References

Spacecraft propulsion Agility drills  are used in the aim of improving sports agility, which is the ability to change direction and accelerate while in motion.

Description 
The ability to change direction while in motion is very important in many sports but especially in team and dual sports. For example, an American football running back must be able to quickly change direction when he sees an opponent preparing to tackle him.  A basketball player must be able to quickly change directions when dribbling the ball, attempting to get back on defense, or when trying to beat an opponent to the ball. A tennis player must be able to quickly change directions when moving to a position where the ball is expected to go but instead finds the ball going in a different direction.

Jumping

Drills that entail jumping with turns in the air are usually applicable to basketball players and receivers and pass defenders in football but can apply to many sports in interest of strength. Drills that use side jumps and front-back jumps are more specific to team sports in which the athlete must change direction while running. Drills that require jumping over objects is usually best suited for sports in which the player must leap over hurdles or players. These drills usually use some form of rope ladders, small or low hurdles, ladders, or small cones.

Ladders, hurdles and cones
The drills that use ladders, hurdles and cones are used extensively in many different sports.

Cutting action
For the drill to be successful in relation to improving sports performance on the field or court, it must include cutting actions. Learning how to do the cutting action is imperative. It involves both technical and physical components that are learned skills. These skills must be mastered in order to get maximum benefit in the agility drill.

References

Physical exercise Rock step (also called break step) may refer to one of several similar dance moves. The name refers to the rocking action during the move: the weight is transferred from one foot to another and then back. It is used in a number of dances, such as East Coast Swing, Zydeco, Lindy Hop, Tango.

Most often it is a two-step dance move executed in two beats of music. There are two basic versions: rock back and  rock forward. They may start with any foot.

Basic rocks
In rock back, the dancer steps backwards with full weight transfer then transfers the weight back to the front foot while keeping it in place. In rock forward, the dancer steps forward with full weight transfer then transfers the weight to the back foot while keeping it in place.

In some dances, e.g., East Coast Swing or Lindy Hop, the partners rock from opposite feet in opposite directions, i.e., both are doing rock back, e.g., during the basic step sequence: "triple step, triple step, rock step". In others the rocks are done from opposite feet, but in the same direction, i.e., when the leader rocks back, the follower rocks forward.

Turning rocks
In some dances (Tango, Argentine tango) the rock step is used to change the direction of travel. In such cases a one or both steps the dancer may perform a certain amount of pivot turn.

In Lindy Hop, the turning rock step is also known as a rotational rock step, due to the rotation of the body's center to change direction or prep for a move. The degree of rotation in the turning rock step varies with how far the dancer wants to change direction. When used as a prep for a move, the degree of rotation depends on how much tension must be built up in the connection between the dancers in order to properly execute the move.

Rock step vs break step
Sometimes the terms rock step and break step are used interchangeably e.g., Forward Rock and Forward Break. The stylistic difference is that in the rock step the emphasis is in the rocking action during the step, while the term break carries the meaning of the change of the direction into the opposite, i.e., the forward break changes the direction of the movement from forward to backward.

Dance variations named "Rock Step"
In Zydeco, the Rock Step is the name of a pattern obtained from the Zydeco's Basic Step  if the leader on count 6 makes a little push for the follower to rock back (on 7,8) and rocks himself back.

References

Social dance steps